Stethoscopes have long been used by physicians to monitor auscultatory sounds. Typically stethoscopes have been comprised of a head or chestpiece, a sound transmission mechanism and an earpiece assembly. The chestpiece is adapted to be placed near or against the skin, body, of a patient for gathering the auscultatory sounds. The sound transmission mechanism transmits the gathered sound to an earpiece, or a pair of earpieces, where the physician may monitor the sound.
The chestpiece of conventional acoustic stethoscopes are usually quite simple physically. They are usually round disk shapes sometimes dual sided, top and bottom, to allow either side of the chestpiece to contact the skin of the patient, perhaps for the gathering of auscultatory sounds in different frequency ranges.
Recently, some stethoscopes have utilized electronics for at least part of the sound processing path. In most of these devices, the auditory sound is picked up by a microphone usually located in a detection device which is similar to the chestpiece of a conventional auditory stethoscope in external appearance. The electrical signal from the microphone is then processed electronically and is coupled to a speaker, or speakers, where the electrical signal is converted back into an auditory sound for reception by the physician. Of course, other electronic analysis or display of the auscultatory sounds may be performed by the signal processor, either in addition to or instead of the usual conversion back into an auditory sound.
The incorporation of electronic circuitry into the stethoscope has been a considerable design problem for the engineer. Typically, the electronic circuitry increases the physical size of the stethoscope package. Either the size of the chestpiece is increased in size dramatically or an additional enclosure to house the electronics is located between the chestpiece and earpiece assembly or both. In both of these cases, the resulting stethoscope is bulky, cumbersome to use and not easily storable between uses.
Since, stethoscopes are by necessity portable devices and since the electrical components of electronic stethoscopes require a source of electrical power, electronic stethoscopes must be battery powered. Also, since the physician has become accustomed to handling and using a conventional acoustic stethoscope, an electronic stethoscope must by physically sized and configured to resemble its conventional acoustic predecessor. Further constraints placed upon the electronic stethoscope include the demands of reliability, long battery life, light weight, isolation from external sounds, maintenance of high signal quality.
U.S. Pat. No. 4,170,717, Walshe, Electronic Stethoscope; U.S. Pat. No. 3,790,712, Andries, Electronic Stethoscope System; U.S. Pat. No. 4,878,501, Shue, Electronic Stethoscope Apparatus; and French Patent Publication No. 2,659,007, Oclin, Stethoscope With Electronic Amplification, generally describe electronic stethoscopes.
U.S. Pat. No. 4,071,694, Pfeiffer, Stethoscope, (assigned to the assignee of the present invention) describes a stethoscope which has both an electronic and an acoustic capability. The chestpiece of the stethoscope described in the Pfeiffer patent has a conventional shape and achieves a conventional function. The chestpiece is round and generally flat making the stethoscope appear and handle similarly to conventional stethoscopes. The stethoscope contains a battery holder (37) formed of an insulating material such as polypropylene placed on top of a printed circuit board (34) clamping the printed circuit board to the housing. In addition to having a pair of cavities (38) for flat, round batteries (39), the battery holder also serves as a cover for the volume control (35) and frequency selector (36). The battery holder is also provided with a cylindrical guide sleeve (40) for push button on-off switch (41)
U.S. Pat. No. 4,254,302, Walshe, Electronic Stethoscope, illustrates a circular holder (194) for two replaceable batteries (190 & 191) contained in wells (192 & 193). The holder is received in body bore (196) against shoulder (197). A metallic terminal strip (198) on disc (199) engages the battery terminals (190a & 191a) when cap (160) is in place. Different sized studs (200 & 201) on the disc (199) interfit locator stud holes (203 & 204) in the holder (194).
Other patents describe various battery powered electronic apparatus but which fail to provide the significant advantages of the present invention.
For example, U.S. Pat. No. 4,075,561, Stevens, Programmable Electrical Apparatus Containing a Battery, describes an electrical apparatus, watt-hour meter, enclosed within a housing which contains a replaceable battery. A composite unit (16) provides the dual functions of battery support and terminal connector and cooperates with an access port or service entry (14) in the housing (12). The composite unit includes an integral structure containing support or receptacle for a battery, such as dry cell battery (18), which may comprise a hollow cylinder or tubular body providing a receptacle or chamber (20) for the retainment of a battery in its designated position within the apparatus and in electrical contact with the terminals therefor. Battery chamber (20) is provided with a plurality of longitudinal spacing ribs (22) for the support of the battery. The composite unit provides connecting terminal (26) for terminal post (24) of the battery and connecting terminal (30) for terminal post (28) of the battery.
Also U.S. Pat. No. 4,391,883, Williamson et al, Housing Arrangement With Breakaway Battery Access Door, describes a battery powered device (10) having a battery compartment with an integral battery door assembly (12). The battery door is hinged permitting outward pivoting from the housing. A latch mechanism (20) may be operated to latch and unlatch the door. The battery door assembly (12) includes two horizontal wing members (28) which cylindrically hold the cylindrical battery (18). When battery (18) is positioned within cavity (16), respective ends thereof are placed in contact with terminals (40) which supply power to the electrical circuitry.
U.S. Pat. No. 4,578,628, Siwiak, Portable Battery Powered Electrical Apparatus With Improved Battery Pack Protected Against Inadvertent Short Circuit of the Battery Terminals, discloses a portable radio transceiver (10) having a removable battery pack (14). The battery pack includes a battery power source (15). The battery (15) makes electrical contact within the battery pack (14) and is coupled to terminals (18) on the battery pack through a normally open switch (20). Switch (20) is not closed until the battery pack is coupled to the transceiver, thus preventing any accidental short circuiting of the battery.
U.S. Pat. No. 4,429,025, Stow, Battery Retaining Device, discloses a retaining device suitable for removably interconnecting a battery with the housing of an electrical apparatus. The retaining device has a bracket provided with two stanchions adapted to receive the battery in a battery retention channel.